tricks of R v4.0.0 [R for BE/BA]

Right. R v4.0.0 requires all packages rebuild for it. The binary file (*.tgz) on SourceForge now was built under previous version (R v3.6.x). So you need to download the source tarball file (*.tar.gz) of bear from here and place it in your working folder (getwd() to know where it is). Then open an terminal, type R CMD INSTALL bear_2.8.7.tar.gz [Enter]. It should work. I have done with upgrade to R v4.0.0 on Windows and macOS (both Mojave & Catalina). Now is waiting for linux-ubuntu (from its software update).

Ps. (1) However packages binary built under R v4.0.0 can be installed for R v3.6.x without any compatibility issue. (2) R v4.0.0 seems running faster on Windows, but much slower on Catalina... just my gut feeling.